1. Field of the Invention
This invention relates to apparatus of the type which is adapted to receive a removable cartridge containing material to be utilized in the apparatus, and more particularly, to means to insure that only a cartridge containing a particular code means can be mounted on the apparatus. One example of such apparatus is a chemical analyzer for performing analyses of biological fluids.
2. Description of the Prior Art
Chemical analyzers have been developed for performing quantitative analyses of biological fluids, such as blood serum, to enable the physician to obtain a more complete picture of a person's physical condition. In one type of analyzer, reagents are added to a sample of blood serum and, after sufficient incubation, a color change or fluorescence is sensed by a radiometer. In a second type of analyzer certain ionic blood components are detected potentiometrically by measuring the potentials generated by ion-selective electrodes.
Most of the commercially-available apparatus for performing quantitative analyses of biological fluid samples utilize liquid reagents and require analyzer equipment having intricate solution handling and transport capabilities. Recent developments, however, have provided test elements in essentially planar, dry form which can be loaded into a cartridge adapted to be removably mounted in an analyzer. In the analyzer, a test element is fed from a cartridge into a metering station where a predetermined amount of sample fluid is deposited on the test element. The element is then removed to a read station where a change in the test element is sensed, the amount of change being proportional to a particular analyte in the sample fluid. The test element is used only once and is discarded after the reading has been taken. An analyzer for use with test elements of this type is described and claimed in commonly-assigned U.S. patent application Ser. No. 856,834, entitled CHEMICAL ANALYZER, filed in the name of Nosco et al. on Dec. 2, 1977, and now U.S. Pat. No. 4,152,390.
Cartridges of the type described above are normally loaded with test elements for performing a single test, for example an analysis of the concentration of sodium ions in blood serum. The cartridges must be generally uniform in size and shape, regardless of the type of test element which they contain, since each of the cartridges must fit into cartridge support structure of fixed dimensions. Serious consequences could result if a cartridge containing the wrong type of element for the test desired is inserted in the analyzer, an event that might occur in a busy laboratory where many samples are analyzed daily. Such erroneous insertion would, of course, result in inaccurate test results and in a loss of valuable time when the analyses must be performed under emergency conditions.
One solution to the problem of assuring that the analyzer will not be loaded with the wrong test elements has been proposed in the aforesaid U.S. patent application Ser. No. 912,288, entitled ARTICLE CONTAINER, now U.S. Pat. No. 4,151,931. In the cited application, removable pins are inserted in holes in a cartridge nest, and each biological test to be performed is assigned a unique pin arrangement. Thus, if pins are properly inserted in the holes, only a cartridge having a predetermined code means can be inserted in the nest. This arrangement, although providing a workable solution to the problem, is time consuming and requires careful manipulation on the part of the operator.
It is known in the clinical apparatus art to provide reagent containers with code means which provide certain information to the apparatus when the container is inserted thereon. The U.S. patent to Carter et al., U.S. Pat. No. 3,770,382, discloses a test pack which comprises machine-readable indicia for identifying the tests for which the pack is intended.
It is also known to provide a reagent container with means to prevent the container from being inserted in the wrong location in an analyzer. The patent to Hartnett et al., U.S. Pat. No. 3,905,772, discloses apparatus for performing blood tests in which a test-tube carrier comprises key members which interact with slots in the apparatus to insure that the carrier will be placed in the proper test station in the apparatus. None of the known prior art devices, however, discloses a means by which the operator can quickly and accurately adjust the apparatus to accept a cartridge containing a predetermined code means and reject all other cartridges not so coded.